Ultrahigh-frequency electric discharge tube



Dec. 22, 1953 G. DIEMER ET AL 2,663,822

ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Filed Nov.. l, 1951 5Sheets-Sheet l INVENTORS Gesinus Diemer Klaus Rpdyhuis Dec. 22, 1953 e.DIEME'R ETAL 2,663,822

ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Filed NOV. 1, 1951 5Sheets-Sheet 2 Gesinus Diemer Kloos RWW By 7/1 Agent Patented Dec. 22,1953 ULTRAHIGH-FREQUENCY ELECTRIC DISCHARGE TUBE Gesinus Diemer andKlaas Netherlands, assignors to Hartford National Bank and TrustCompany, Hartford, Conn., as

trustee Rodenhuis, Eindhoven,

Application November 1, 1951, Serial No. 254,274

Claims priority, application Netherlands November 4, 1950 Claims.

This invention relates to circuits comprising electric discharge tubeswhich are suitable for short operation at short and ultra-shortwavelengths, i. e. wavelengths of several metres down to approximatelyone centimetre and which comprise at least a cathode, a, control gridand an output electrode. The last-named electrode in a normal triode,tetrode or pentode is the anode; for the centimetric range'it issubstantially only triodes that enter into account.

In order to make such tubes serviceable, for example as amplifiers, atas short a wavelength as possible, vefforts have been directed towardsminimizing the capacity between the input electrode and the commonelectrode on the one hand and between the common electrode and outputelectrode on the other hand. At wavelengths that are not excessivelyshort the cathode is usually the common electrode. With tubes comprisingdisc-shaped electrode leads suitable for ultra-short waves, the controlgrid is usually the common electrode. .The capacity between thedifferent electrodes depends not only upon the surface area of theelectrodes and their relative spacing but also upon unavoidableparasitic capacity.

If that part of the capacity between the electrodes which is directlyproportional to theactive surface is termed the effective capacity, itis well known that the effective capacity of a sim-' ple flatarrangement equals wherein 0=the active electrode surface and d=thespacing. For more intricate arrangements the effective capacity may becomputed as the sum of a number of terms or in an integral form. Thatfraction of the total capacity that is not constituted by the effectivecapacity as defined will hereinafter be termed the ballast capacity."

In view of the necessity for maximum reduction of the tube capacities itis first essential to minimize the ballast capacity. However, for eachelectrode arrangement there is a minimum which may not be passed owingto the capacity of the wiring and supply conductors. For tubeconstructions comprising fiat electrodes and lead-through discs sealedinto the wall of the tube, this minimum is lower than for tubes with aconcentric arrangement and pin-shaped elec trode leads. I

As a rule the effective capacity must be comparatively high, since inparticular the cathode two ratios and the product' thereof are equal to2 I 7 surface must usually not be loaded above a given current densityand the surface area must satisfy the desired power requirement.

According to the present invention in a circuit comprising an electricdischarge'tube for short and ultra-short waves, the tubes including atleast a cathode, a control grid'and an output electrode, the product ofthe ratios of the effective capacity and the ballast capacity betweenthe input electrode and common-electrode and between the commonelectrode and the output electrode lies between and l, each of theseratios has a value between /2 and 2. The product of the two ratiospreferably equals or approximately equals unity. In the optimum each ofthe two ratios equals unity. h I

The power gain attainable with the tube'in'the' case of completematching is a maximum if the each other and unity respectively. 'Ifthe'two ratiosare each 2 or /2 the attainable power gain is 25% lower thanthe maximum, again with complete matching. This holds if the 'ohmicdampings preponderate relatively to the electronic dampings as isusually the case at very high frequencies. If the electronic damping iscomparatively high, the power decrease is "reduced. The feedback due tothe self-inductance of the grid wires of the tube should be small and inabsolute value substantially equal the feedback due to the capacitybetween the anode and cathode.

V The'reasoning behind the choice of the aforesaid ratios and thisproduct may be explained as follows; The maximum attainable power gaindepends upon the mutual conductance of the tube, which generally has acomplex value for high frequencies. Furthermore the power gain dependsupon the input damping, the output damping and the feed-back in thetube. As a rule, the power gain with a non-excessive feed-t back willapproximately be inversely proportionalto the product of the inputandoutput-damping, expressed as conductances, and substantially directlyproportiona1 to the square of the absolute value of the mutualconductance. At very high frequencies the input-.-' and output-damping'slargely depend upon the respective total capacity, effective and ballastcapacity together; since the charging and discharging of thesecapacitances must take place through the series-resistors formed by thesupply conductors and does not appreciably depend vupon the size of theelectrode.

surfaces.

The correctness of the aforesaid criteria may be conformed from theconsiderations in an article by Knol and Van der Ziel in PhilipsResearch, vol. 4, pages 168 to 178, 1949. Referring to Formula'zfiiaheielhffer thfih 'wiiihiifii power ain amt; at an arbitrary fourteri'rriha l network in the case of optimum tuning and matching at theinput and output side and an arbitrary given feedback, it holds thatvihiil'it rg R input resistance efl"ect1ve part of I input with openoutput f ack resistance=eective part of I input With shorteircu itedinput V R foward resistairoe iafi'h'ti i 'e ears of --1 outpu phaseangle, i'ortvard admittance Alithe'aaiifiitttifiees mhs'is't f anelectronic and a nonelectmnic srq'the "1 tter'eqnsistm '0; theohiiiieibs'ses. The ei" ron 'c l part 'i invariably prapoitiaiiai ta thattire. serrate the to the eet'fife'capaity. iThe'non electrbnic partsare rae rtfionei to t e iif'theto'tal capacity.

I the an; aid'forinula'eveiything is expressed"? the ra-t etten thestream-capa gmair has a maxim'irm if it t? i i d, "ba la t eapa ty al'fii iictiofn 36f this rat'i'o eau'ai ifinity. a p p H V artertharthe iivenffiient ay be 'inoi'e clearly shes 'vfil 310w gee f ame is "theafcco'iiipanyi'ng rasm'esieiveafbyiwey 'o'f sesame, in w ich; I --Y'fig1"f"". '71 mattresses-t ase s stem orekiiewh'eaiibieeentadeahu 13$. 2and {S are longitudinal sections of the elitiiod s nergies? s eet/i1 tibes comprising dlscaha' semieaamu members and e; a triodecbifiiirrsiiie ms fhja'pe'd lea'd oiit members forus'acetriirie'summarises. a

frhe'fdrfiieiisiefis 6f t e 'ioubi'pjeiitoee shown in FEE, 1; "afi' a'rirofn l the "shale given. For sash,

fientoife ljdi'iotes thqtxwasra 231 's send- 1 gridlanaf'ttnescree' rid.The suppressor grid 4 ei eoilfstrated asia ape srea fsereenena iscoiifri'ion ts fb tifitehtbae In thise-Tectrole system, it may be takenthat the ballast capacity is present only at the ends dsystem and in thewiring, from which it can be deduced that for the reduced grid theefieetive capacity=2.05 pf, and the ballast capacity=3.25 pf. For thereduced anode the efiective "capacity is L55 pf, andtheballastpapacityf-lzfl pf gthe two ratios between effective capacity and ballast capacitythen being and and the-product 0:95; 7

For the known tube the ballast capacities-are the same and the efiectivecapacities for :grid'and anode are $.16 and 4:5- pf. respectively, sothat the ratios'are and a d the productfit. V p

'In the k' ip' n tats shewn i'n-FigQ-E; aeyiindrrcal ensue block arese'ied "to a Qi'iddisc fttfby means of a conical glass head 9. A glass ueehstjitutes thejdiht petween diesels and a oathd'debylin jl-"a. Byinefans oflass beads two hest'er supeiy eon'aiietors1&4 a d a-"cathodesueei semester is aie' sea lejd 11; "the base 13. The exhausttube is designates fifties filament '1"! and the cathode 8. The activesurface of the cathode carries a thin iiifide layer (not shown). Thecathode I8 is Welded with thec aid of foil [9 tothe flanged ame I. llts'fia'rigj'e 'is emits-ea between two-s same rings- '22 and 23'iaiidfo'entred 'bya 2e au ts-sting ith the" 'supei 'emauc'tor 1"6. rhcatu'oee is electric-any separated fr'om the vpyimesa;{ i y means at aninsulating ring 25. ine 'fdohTstiiifcftionis diain'iieatbeether by meansof foui""'spiings 26 extendme from ring 2'! and strained by cylinder 23.The cerairi'ic'i ine 22 bears ees eripir asrestr g' "on "the oathod'e sd' H or "grid 11 mg 30*which has secured thereto rrautyfdrem "wires. Bymeans is sue-melt: tamer-mes! are secure three 5161s preview at apelest: in rme'fz. Ks's'tated this construction isk'llown; it is 'fg ive nto .permit direct contrast with a cerrespthuin tube; for use according"to inventive 'shoiva in' Fig. 3. in Fig. 3 the cathbd'e Quee s anoeuiscsa're' design'ated 31, e2; 33 respective'1yf34 'be'ing'a'cylindrical anode. :Ifhegrid ring 375 rests with its w'irewound-side esaeams theerii disc. A porous tungsten hood containing. a supply ofbariumstrontium oxide 38 is designated 31. The cathode is connected tothe cathode disc through foil 39. This tube is shown in lesser detailthan the tube shown in Fig. 2, since there is no necessity to describepoints following known tube-technique.

In the following table constructional data and properties are given forthe known tube shown in Fig. 2 and for the tube shown in Fig. 3.

Ratio between effective and ballast capacity:

Cathode-grid Grid-anode Product of ratios between effective and ballastcapacity. Attainable power gain at wave length. Supplied powerCorresponding anode cur- 10 X7.5 cms rent and mutual con- 50 umductance.

The capacities stated in the table are those of the tube without thecapacities through the glass of the bulb. It is obvious that in the tubeshown in Fig. 3 the total capacity between cathode and grid ismaterially lower. Moreover, the cathodegrid spacing through the bulbwall is simpler than through the foil shown in Fig. 2. The mutualconductance of the tube shown in Fig. 3 is one fourth of that shown inFig. 2 and notwithstanding that, the power gain at the same wavelengthsimilarly corresponds to the power supplied. This equally-satisfactoryoperation, despite the larger cathode-grid spacing and the low mutualconductance, is for the major part due to the favourable ratio betweeneffective capacity and ballast capacity,

What we claim is:

1. An electric discharge tube comprising a cathode, an output electrode,and a common electrode interposed between said cathode and outputelectrode, said common electrode and said cathode electrode havingactive surface portions spaced apart a distance at which there is agiven effective capacitance and a given ballast capacitance between saidcathode and said common electrode, the ratio of said capacitances beingbetween and 2, said output electrode and said common electrode havingactive surface portions spaced apart a distance at which there is agiven effective capacitance and a given ballast capacitance between saidoutput and common electrode, the ratio of the latter capacitances beingbetween /2 and 2, said electrodes further being spaced from each other adistance at which the product of said ratios is between and 4.

2. An electric discharge tube comprising a cathode, an output electrode,and a common electrode interposed between said cathode and outputelectrode, said common electrode and said cathode electrodehaving'active surface portions spaced apart a distance at which there isa given effective capacitance and a given ballast capacitance betweensaid cathode and said common electrode, theratio of said capaQitancesbeing between and 2, saidou'tput electrode and said common electrodehaving active surface portions spaced apart a distance at which there isa given effective, capacitance and a given ballast capacitance betweensaid output and common electrode, the ratio of the latter capacitancesbeing between /2 and 2, said electrodes further being spaced from eachother a distance at which the product of said ratios is unity.

3. An electric discharge tube comprising a cathode, an output electrode,and a common electrode interposed between said cathode and outputelectrode, said common electrode and said cathode electrode havingactive surface portions spaced apart a distance at which there is agiven effective capacitance and a given ballast capacitance between saidcathode and said common electrode, the ratio of said capacitances beingapproximately unity, said output electrode and said common electrodehaving active surface portions spaced apart a distance at which there isa given effective capacitance and a given ballast capacitance betweensaid output and common electrode, the ratio of the latter capacitancesbeing approximately unity, said electrodes further being spaced fromeach other a distance at which the product of said ratios isapproximately unity.

4. An electric discharge tube comprising a cathode, an output electrode,a common electrode interposed between said cathode and output electrode,said common electrode and said cathode electrode having active surfaceportions spaced apart a distance at which there is a given effectivecapacitance and a given ballast capacitance between said cathode andsaid common electrode, the ratio of said capacitances being between /2and 2, said output electrode and said common electrode having activesurface portions spaced apart a distance 'at which there is a giveneffective capacitance and a given ballast capacitance between saidoutput and common electrode, the ratio of the latter capacitance beingbetween /2 and 2, said electrodes further being spaced from each other adistance at which the product of said ratios is between A and 4, andterminal wires for said common electrode, said terminal wires having aself-inductance at which feed-back introduced thereby equals thefeed-back introduced through inter-electrode capacitance between thecathode and output electrode.

5. An electric discharge tube comprising a cathode comprising ahollowbody of refractory metal having a cavity therein, one wall of said bodyadjoining said cavity being porous, and a supply of alkaline earthoxides in said cavity, an output electrode, and a common electrodeinterposed between said cathode and output electrode, said commonelectrode and said cathode electrode having active surface portionsspaced apart a distance at which there is a given effective capacitanceand a given ballast capacitance between said cathode and said commonelectrode, the ratio of said capacitances being between and 2, saidoutput electrode and said common electrode having active surfaceportions spaced apart a distance at which there is a given effectivecapacitance and a given ballast capacitance between said output andcommon electrode, the ratio of the latter capacitance being between and2. said electrodes Iurther being spaced from each other a distance a:which the product bf said r'atid's is between /4 and 4;

GESINDS DIEMER.

Number Name Number mms 2,121,589 2,131,204 2,353,?42 2,353,743 2,391,9232 1 1 3.? 2,416,565

Name Date H1111 at al Feb. 8, 1933 Espe i June 21 1938 Walfic-hmidtSept. 22, 1938 Jury 1'3, 1944 McA'r'tnur July 18, 194 jsgerstrom, Jr."Jim 1, 1946 Bggs Nov. 19, 1946 Bg'gs Feb. 25, 1947

